Bill,
Thanks again for letting me participate in your discussion and adding links to our information.
In regards to your question on the overcurrent protection knowledge needed by the average electrician, I would suggest the below three most important points, in order of importance.
1) Always make sure you know the available fault current and apply an overcurrent devices with adequate interrupting ratings per NEC 110.9. This is the most overlooked and important item of proper overcurrent protection. This is especially important for the service equipment and first level distribution panelboards. The application of current-limiting devices makes this less of an issue in these applications due to high interrupting rating capabilities.
2) Be aware of proper protection requirements of electrical systems components per NEC 110.10 and NEC 110.3(B). Many components may require a specific device, per NEC 110.3(B) in regards to the listing and labeling...such as HVAC equipment. This can also be extended to motor circuits, regardless of the single-phasing concerns. Fuse protection (with solid state overloads and single phase protection) are still the best solution for these applications.
3) Safety is the common thread in overcurrent protection. The first two points have addressed safety in regards to systems and electrical components, because this is the most common concern. However, when you add the human factor...this hits home even more and this is why this has been a major focus recently. Anyone who has seen an electrician with third degree burns understands what I am referring to with this discussion. I am not trying to imply that fuses solve all the problems in protecting the electrician, however they certainly help to offer a component of the total solution. The bottom line is that fuses can provide reliable overcurrent protection and can lessen the dangers to electricians in certain situations.
